1. Field of the Invention
The present invention relates generally to robotic media storage library systems, and more specifically to a redundant system that includes a plurality of independent robots in the form of robotic pods.
2. Background of the Invention
The current enterprise class library system contains multiple independent robots for concurrently manipulating multiple media cartridges. The library system comprises an array of media storage cells and media cartridge players. A system of rails is used to guide robotic pods through all of the locations on the array.
The current enterprise class library has a few redundant features, such as the Hand and the Hand Servo Controller. However, it still has many potential single points of failure in the robotics electrical components (i.e. main controller, interrupt controller, etc.). If a failure occurs in one of these components, it may make the unit non-operational. Currently, there is a customer demand for high availability (99.999% run time) on enterprise class tape automated libraries, which requires minimum system down time due to individual component failures.
Therefore, it would be desirable to have a method for providing redundant controllers that mirror each others"" function and can immediately take over if the primary control units fails.
The present invention provides two redundant tape library controllers that mirror each other""s function. A secondary controller can immediately take over from the primary controller if the primary unit fails or if a redundant path leading to the primary controller fails.